Controlled atmosphere furnace muffle



Dec. 17, 1957 e. F. TISINAI ETAL CONTROLLED ATMOSPHERE FURNACE MUFFLE 2Sheets-Sheet 1 Filed Dec. 29, 1955 ebs I Ma.

ATTORNEY 2 Sheets-Sheet 2 INVENTORS: Geaage 7 'isinai Ham 0' A. B/rknessJohn R. Krebs Dec. 17, 1957 e. F. TISINAI ETAL CONTROLLED ATMOSPHEREFURNACE MUFFLE Filed Dec. 29, 1955 A TTO/iWEY United States PatentCONTROLLED ATMOSPHERE FURNACE MUFFLE George F. Tisinai, Highland, lnd.,Harald A. Birkness, Homewood, Ill., and John R. Krebs, Indianapolis,Ind, assignors to StandardOil Company, Chicago, IlL, a corporation ofIndiana Application December 29, 1955, Serial No. 556,135

6 Claims. (Cl. 266-4) This invention relates to heat treating apparatusand, more particularly, to metal treating furnaces. It is concerned withimproved means for the transfer of work pieces to and from a mufilewhile maintaining the work in a protective or processing atmosphere.

It is desirable to conduct certain heat treatments at temperatures inexcess of 2000 F. and in an atmosphere other than air. However,apparatus heretofore available has been unsatisfactory for one or moreof several reasons. Many such furnaces are not continuous in operation,do not provide for the treatment of several work pieces for varyinglengths of time, do not include quenching means which can be utilizedwithout removing the specimen from the protective atmosphere, and havenot provided for remote handling of the specimens.

It is, therefore, a primary object of our invention to provide a muffiewhich permits quenching without removal from the protective atmosphereand with choices of two or more quenching media. A further object is toprovide a muffle adapted for continuous transfer of specimens by meansof remote handling tongs and retractable radiation shields. Stillanother object is to provide a furnace mufile adapted for controlledatmosphere heat treatments of several specimens for varying lengths oftime. Another object is to provide an apparatus which permitsmaintaining uniform temperature in the heated section and is of simpleconstruction to avoid thermal lags. These and other objects of theinvention will become apparent as the description thereof proceeds.

Briefly, our invention comprises a storage chamber and a mufiie whichare both maintained under a controlled atmosphere. A plurality of quenchtanks are arranged below the storage and transfer chamber with access tothe quench tanks both from within and without the storage chamber. Theliquid in the quench tanks serves as a quenching medium and as a sealfor the furnace. Thus, samples can be removed from the quenching tankswithout interrupting the operation of the muflle. A plurality of bafilesextend across the inlet to the muffle, the bafiles being controllablefrom the exterior of the apparatus. A pair of handling tongs permit themanipulation of the work pieces within the storage chamber and themutlie. Further design features and advantages of our apparatus will bedescribed in connection with a preferred embodiment of the inventionillustrated in the accompanying drawings wherein:

Figurel is an isometric view of the assembly;

Figure 2 is a top view of the apparatus shown in Figure 1; and

Figure 3 is an enlarged detail of one handling tong assembly.

Referring to Figure 1, we provide a storage chamber having a front panel11 and a roof or top panel 12. The front panel 11 is provided with awindowed door 13 and the roof 12 with a window 14. An end of the hearthchamber 15 is integral with the storage chamberltland extends through afurnace wall 16 as schematically shown in Figure 2. Within themufllechamber 15 are a pair 2,816,751 Patented Dec. 17, 1957' of hingedbaffles 17 and 18 linked by rod 19. The bafile 17 is hinged to the endof the baflle rod 20 which extends through the panel 11.

When the baffle control rod 20 extending through the front panel 11 ispulled out both baffles 17 and 18 swing outwardly. With such anarrangement, it is preferred that the hinges 43 and 44 be fixedhorizontally below the roof 12 of the mufile chamber 15.

A thermocouple well 21 has access from the front panel 11 and extendsthe length of the storage chamber 10 and muflle chamber 15. A waterjacket 22 having inlet 23 and outlet '24 encircles a portion of thehearth chamber 15 adjacent the storage chamber 10. The blanketing gas isintroduced by inlet duct 25 and is discharged at the remote end 15a ofthe muffle chamber 15. The effiuent blanketing gas from the apparatus isvented by means of nipples 26 spaced from each other in roof 12. Conduits (not shown) are connected to the nipples 26and manifolded for flowthrough a liquid bubble trap (not shown) and vented into a hood.

The specimens to be treated are initially introduced into the storagechamber 10 by way of door 13 as described and then into hearth chamber15. This may be done in two steps or stages. First the tongs 27 may beused to move the specimen from the storage chamber 10 to a point infront of the baffle 17. Window 14 in the top panel 12 and a lightprojected through port 28 facilitate the manipulation of the samples.

A second pair of tongs 29 can then be used to transfer the work piecesfrom the storage chamber 10 into the muffle chamber 15. This isaccomplished by first retracting baffle rod 20 to open the baffies 17and 18, after which the tongs 29 are used to carry the work piece intothe mufiie chamber 15. During this operation, the water jacket 22assists in preventing excess heat transfer into the storage chamber 1tand quench tanks 30 through floor ports 31.

It will be noted that each of tongs 27 and 29 are provided with flexiblebellows 32 and 33 adjacent the front panel 11. This permits considerablefreedom of movement with the specimen tongs and enables the operator toreadily manipulate the specimens within the storage space, to and fromthe hot zone of the muffle chamber 15 and into the quench tanks 30 and3011. If desired the shorter tongs 27 can be mounted in side wall 34 ofthe storage chamber 10.

Tong support plate 35, removably fixed to the front panel 11 is providedwith a window 36 which further facilitates the observation andmanipulation of the work pieces. When it is desired to withdraw atreated sample, the procedure is reversed and the treated specimen iscarried rearwardly to a point adjacent the quench ports 31 and 31a.Tongs 27 or 29 may be used to drop a heattreated sample into theselected quench tank 30 or 30a. The depending fixed ballles 3'7 and 38provide, with the quenching media, a liquid seal between the storagechamber 14 and the ambient atmosphere.

Referring to Figure 3, the tongs 29 (and 27) comprise a pair of handles40 with a rod-in-tube assembly 41 connected to the corresponding jaw 42and 42a.

In operation the muffle chamber 15 is projected through a furnace wall16. The furnace is started and as heating progresses, the quench tanks30 and 3th: are filled, the specimens are introduced through door 13 andthe cooling water flow rate through the jacket 22 is adjusted. Theapparatus is purged with the gas desired for a protective atmosphere andwhen the desired temperature, as indicated by a thermocouple located inthe thermocouple well 21', has been reached the specimens are placedwithin the hot zone of the muffle chamber 15 for the required time andtreatment. During the treatment, the baffles 17 and 18 are arranged intheir closed position. A refractory 3 panel can be provided on thebattle faces toward the hearth chamber 15.

The space within the storage chamber allows the operator to place aconsiderable number of samples within the apparatus and then a few at atime can be introduced into mufile chamber without cooling the apparatuseach time a new batch of samples is to be placed in the hot zone. Also,the space within the storage chamber 10 provides ample room for coolingin the protective atmos phere.

When the treatment is completed, the baflles 17 and 1B are opened longenough to retrieve the samples with the tongs 29 and then closed. Thespecimen may then undergo normal cooling within the protectiveatmosphere within storage chamber 10 or be dropped into one of quenchtanks 30 or 30a and removed therefrom through access ports 46 and 46a byany suitable tongs (not shown).

Although we have described our invention with respect to a preferredembodiment thereofillustrated in the drawings, it should be understoodthat this is by way of example only and that our invention is notnecessarily limited thereto. Further, it is contemplated thatmodifications can be made in the apparatus and in the mode of operationof the apparatus in view of our disclosure and that such modificationscan be made without departing from the spirit and scope of theinvention.

What we claim is:

1. An improved furnace muffle including an elongated hearth chamberclosed at one end and open at the other, said chamber comprising thetreating zone of the mufile, storage chamber means having a port thereinmerging with the open end of said hearth chamber, water jacket meansencircling the hearth chamber adjacent said port, dual quench tank meansdisposed subjacent to said storage chamber means and projectinglaterally of a side wall of said storage chamber, access port means inthe floor of said storage means into said subjacent quench tank means, apair of removable panel means on a front wall of said storage chambermeans, one of said panel means including a window and being adapted tobe removed to introduce the specimens to be stored before being heattreated, the second of said panel means comprising a second window andsupporting a flexible bellows through which a tong means extends intosaid storage chamber and into said hearth chamber, and conduit inlet andoutlet means for flowing controlled atmospheres longitudinally of saidhearth chamber to be introduced into said hearth chamber adjacent theclosed end thereof and to be vented from said storage chamber.

2. A controlled atmosphere muflle which comprises in combination aspecimen storage chamber, a hearth chamber closed at its remote end,conduit means between said hearth chamber and said storage chamber,cooling jacket means on said hearth chamber adjacent said storagechamber, tandem radiant heat bafiles interposed said hearth chamber andsaid cooling jacket, rod means extending exterior of said storagechamber adapted to manipulate said baflies, quench tank means disposedbelow said storage chamber, first quench tank access port means in thefloor of said storage chamber, tong means slidably extending through awall of said storage chamber and adapted to be manipulated within saidhearth chamber, second access port means for said quench tank meansexterior of said muffie, said quench tank means including a liquid sealmeans comprising 21 depending extension of a side wall of said storagechamber, conduit means for flowing a controlled atmosphere into andthrough said muflle from the closed end of said hearth chamber into saidstorage chamber, and vent means in said muflle by which said controlledatmosphere may be discharged.

3. A furnace muflle comprising unitary treating chamber means andstorage chamber means, said treating chamber means being elongated andadapted to be supported within a furnace, radiant heat bafile meansdisposed across said treating chamber adjacent said storage chamber,said bafiie means comprising a pair of spaced hinged and articulateddoors, baffle control means extending through said storage chamber formanipulating said radiant heat baffle means, quench tank means arrangedbelow a portion of said storage chamber, quench tank port means in thefloor of said storage chamber above said tank means, inlet duct meanssupplying gasiform fluids directly to said treating chamber, outletmeans for venting said gasiform fluid from said storage chamber, saidinlet duct and outlet conduit means providing circulation of gasiformfluid into and from the mufile, and tong means slidably supported by awall of said storage chamber and extendable from said storage chamberinto said treating chamber.

4. Furnace muflle means including in combination an elongated treatingchamber adapted to be supported within a furnace, a storage chamber incommunication with said treating chamber and having a portion thereof inalignment therewith, radiant heat bafile means disposed within saidtreating chamber adjacent said storage chamber, said baflle meansincluding a pair of hinged door members disposed across said treatingchamber, a link rod between said doors, and a bafile rod hinged to oneof said doors and extending through said storage chamber formanipulating said doors in unison, water jacket means surrounding saidtreating chamber means between said baffles and said storage chamber,quench tank means disposed below a portion of said storage chamber inalignment with said treating chamber, quench tank port means in thefloor of said storage chamber above said quench tank means, access portmeans to said quench tank means exterior of said storage chamber,windows in said storage chamber, gas inlet and outlet means forcirculating a controlled atmosphere through said muflle from a remoteportion of said treating chamber into said storage chamber, and tongmeans supported by a wall of said storage chamber and extendabletherethorugh beyond said baffles and into said treating chamber.

5. In a heat treating apparatus comprising a storage chamber adapted toconfine a protective atmosphere, an elongated treating chamber extendingrearwardly from the rear wall of said storage chamber, and a quench tankmeans below the storage chamber the improvement which comprises firstaccess port means for said quench tank means in the floor of saidstorage chamber, second access port means to said quench tank meansexterior of said storage chamber and arranged laterally of said firstaccess port means, a bay in said storage chamber disposed laterally ofsaid first access port means and in open communication with said storagechamber, fixed batfle means depending from said storage chamber adjacentsaid first access port means and extending to a point adjacent butspaced from the bottom of said quench tank means, said fixed baffletogether with quench liquid in said quench tank forming a liquid sealbetween the storage chamber and the ambient atmosphere, a pair of hingedradiant heat bafiles arranged in tandem across the cross-sectional areaof said elongated treating chamber, link means for manipulating saidtandem radiant heat baflles in unison, conduit means for introducing theprotective atmosphere into the remote rear portion of said treatingchamber, outlet conduit means in said storage and auxiliary storagechambers for flowing protective atmosphere from the apparatus, andcooling jacket means about said treating chamber intermediate saidtandem baffles and said storage chamber.

6. The apparatus of claim 2 which includes a second tong meansextendable through a wall of said storage chamber for manipulation ofspecimens therewithin, and window means in the top wall of said storagechamber to permit viewing such manipulation of specimens in the storagechamber.

(References on following page) 5 6 References Cited in the file of thispatent FOREIGN PATENTS UNITED STATES PATENTS 514,106 Great Bl itain Oct.31, 1939 Brierer Aug. 24,1897 OTHER REFERENCES Allenson Apr. 19, 1910Gier y 21, 1942 5 on'fhe Iron Age, September 23, 1954 (page 116 rehedNorton Apr. 17, 1945 Holcroft Feb. 16, 1954 'Ipsen May 29, 1956

